1. Field of the Invention
The invention relates to a touch input device, and more particularly to an electromagnetic-type touch input device, and a touch display device incorporating the same.
2. Description of the Related Art
Referring to FIGS. 1 and 2, a conventional touch display device 9 is shown to use with an electronic stylus 8 capable of radiating an electromagnetic wave signal. The conventional touch display device 9 includes a liquid crystal display (LCD) module 91, an electromagnetic-type touch panel 92 (not shown in FIG. 1) disposed under the LCD module 91, and a frame 94 for holding and receiving the LCD module 91 and the electromagnetic-type touch panel 92 therein. The LCD module 91 has a rectangular display area 911 exposed from the frame 94. As shown in FIG. 2, the electromagnetic-type touch panel 92 includes a sensor board 921, an X-axis multiplexer 922, a Y-axis multiplexer 923, and a controller 924. The sensor board 921 includes an X-axis antenna array consisting of a plurality of X-axis antenna coils and coupled to the X-axis multiplexer 922, and a Y-axis antenna array consisting of a plurality of Y-axis antenna coils and coupled to the Y-axis multiplexer 923. The sensor board 921 senses the electromagnetic wave signal from the electronic stylus 8 upon a touching by the electronic stylus 8 on the display area 911 so as to output respectively an X-axis sensing signal and a Y-axis sensing signal to the X-axis and Y-axis multiplexers 922, 923. The controller 924 is connected electrically to the X-axis and Y-axis multiplexers 922, 923, and is operable to control the X-axis and Y-axis multiplexers 922, 923 to output the X-axis and Y-axis sensing signals to the controller 924 such that the controller 924 generates an input signal corresponding to a location of a touch point of the electronic stylus 8.
In such a conventional touch display device, when the touch point of the electronic stylus 8 is located within a periphery portion of the display area 911, due to external interferences, the sensor board 921 cannot accurately sense the electromagnetic wave signal from the electronic stylus 8. Therefore, complicated calibration for the periphery portion of the display area 911 is required for the touch panel 92. In addition, when the touch point of the electronic stylus 8 is located on a peripheral non-display area 912 of the LCD module 91 surrounding the display area 911 and covered by the frame 94, the touch panel 92 will not generate any input signal, i.e., it is regarded as a non-useful operation. Therefore, improvements may be made to the above techniques.